Make doc comment parsing for code model external elements a bit more robust

src/VisualStudio/Core/Impl/CodeModel/ExternalElements/AbstractExternalCodeElement.cs

@@ -57,6 +57,20 @@ protected virtual EnvDTE.vsCMAccess GetAccess()
             return CodeModelService.GetAccess(LookupSymbol());
         }
 
+        private static bool TryParseDocCommentXml(string text, out XElement xml)
+        {
+            try
+            {
+                xml = XElement.Parse(text);
+                return true;
+            }
+            catch (XmlException)
+            {
+                xml = null;
+                return false;
+            }
+        }
+
         protected virtual string GetDocComment()
         {
             var symbol = LookupSymbol();
@@ -73,13 +87,15 @@ protected virtual string GetDocComment()
             }
 
             XElement xml;
-            try
+            if (!TryParseDocCommentXml(documentationCommentXml, out xml))
             {
-                xml = XElement.Parse(documentationCommentXml);
-            }
-            catch (XmlException)
-            {
-                return string.Empty;
+                // If we failed to parse, maybe it was because the XML fragment represents multiple elements.
+                // Try surrounding with <doc></doc> and parse again.
+
+                if (!TryParseDocCommentXml($"<doc>{documentationCommentXml}</doc>", out xml))
+                {
+                    return string.Empty;
+                }
             }
 
             // Surround with <doc> element. Or replace <member> element with <doc>, if it exists.
@@ -88,7 +104,7 @@ protected virtual string GetDocComment()
                 xml.Name = "doc";
                 xml.RemoveAttributes();
             }
-            else
+            else if (xml.Name != "doc")
             {
                 xml = new XElement("doc", xml);
             }

src/VisualStudio/Core/Test/CodeModel/CSharp/ExternalCodeClassTests.vb

@@ -22,6 +22,20 @@ class C$$
             TestDocComment(code, "<doc>" & vbCrLf & "  <summary>This is my comment!</summary>" & vbCrLf & "</doc>")
         End Sub
 
+        <ConditionalWpfFact(GetType(x86)), Trait(Traits.Feature, Traits.Features.CodeModel)>
+        Public Sub DocComment2()
+            Dim code =
+<Code>
+/// &lt;summary&gt;This is my comment!&lt;/summary&gt;
+/// &lt;remarks /&gt;
+class C$$
+{
+}
+</Code>
+
+            TestDocComment(code, "<doc>" & vbCrLf & "  <summary>This is my comment!</summary>" & vbCrLf & "  <remarks />" & vbCrLf & "</doc>")
+        End Sub
+
 #End Region
 
         <ConditionalWpfFact(GetType(x86)), Trait(Traits.Feature, Traits.Features.CodeModel)>

src/VisualStudio/Core/Test/CodeModel/VisualBasic/ExternalCodeClassTests.vb

@@ -21,6 +21,19 @@ End Class
             TestDocComment(code, "<doc>" & vbCrLf & "  <summary>This is my comment!</summary>" & vbCrLf & "</doc>")
         End Sub
 
+        <ConditionalWpfFact(GetType(x86)), Trait(Traits.Feature, Traits.Features.CodeModel)>
+        Public Sub DocComment2()
+            Dim code =
+<Code>
+''' &lt;summary&gt;This is my comment!&lt;/summary&gt;
+''' &lt;remarks /&gt;
+Class C$$
+End Class
+</Code>
+
+            TestDocComment(code, "<doc>" & vbCrLf & "  <summary>This is my comment!</summary>" & vbCrLf & "  <remarks />" & vbCrLf & "</doc>")
+        End Sub
+
 #End Region
 
         <ConditionalWpfFact(GetType(x86)), Trait(Traits.Feature, Traits.Features.CodeModel)>